There is a growing challenge in the area of electro-migration (EM) failure for integrated circuit (IC) products, driven mainly by aggressive scaling of interconnect wires. At a high level, EM is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. For example, EM is an electronic-current-induced diffusion due to an electron wind force on metal atoms in the interconnect wires and other conductors in integrated circuit products. This force originates from scattering events with flowing electrons, whereby atoms migrate via a vacancy exchange mechanism. EM is process-dependent, materials-dependent, and layout-specific and is accelerated by higher temperature and current density.
As devices shrink or scale down, power density and hence temperature rise for high performance circuits. At the same time, scaling interconnect pitch increases current density. Both higher temperature and current density result in an increased EM risk for future generations of semiconductor circuits.